Method and system for optical stimulation of nerves

ABSTRACT

An optical-signal vestibular-nerve stimulation device and method that provides different nerve stimulation signals to a plurality of different vestibular nerves, including at least some of the three semicircular canal nerves and the two otolith organ nerves. In some embodiments, balance conditions of the person are sensed by the implanted device or external device, and based on the sensed balance conditions, varying laser nerve-stimulation signals are sent to a plurality of the different vestibular nerves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of and claims benefit of

U.S. patent application Ser. No. 13/225,408 filed Sep. 3, 2011, titled“VESTIBULAR IMPLANT AND METHOD FOR OPTICAL STIMULATION OF NERVES”,(issued as U.S. Pat. No. 8,317,848 on Nov. 27, 2012), which is adivisional of U.S. patent application Ser. No. 11/971,874 filed Jan. 9,2008, titled “METHOD AND VESTIBULAR IMPLANT USING OPTICAL STIMULATION OFNERVES” (issued as U.S. Pat. No. 8,012,189 on Sep. 6, 2011), whichclaims benefit ofU.S. Provisional Patent Application No. 60/884,619 filed Jan. 11, 2007,titled “Vestibular Implant Using Infrared Nerve Stimulation”; ofU.S. Provisional Patent Application No. 60/885,879 filed Jan. 19, 2007,titled “Hybrid Optical-Electrical Probes”; and ofU.S. Provisional Patent Application No. 60/964,634 filed Aug. 13, 2007,titled “VCSEL Array Stimulator Apparatus and Method for LightStimulation of Bodily Tissues”;each of which is incorporated herein by reference in its entirety.

This invention is also related to prior

U.S. patent application Ser. No. 11/257,793 filed Oct. 24, 2005, titled“Apparatus and Method for Optical Stimulation of Nerves and Other AnimalTissue” (which issued as U.S. Pat. No. 7,736,382 on Jun. 15, 2010);

U.S. patent application Ser. No. 11/536,639 filed Sep. 28, 2006, titled“Miniature Apparatus and Method for Optical Stimulation of Nerves andOther Animal Tissue” (which issued as U.S. Pat. No. 7,988,688 on Aug. 2,2011);

U.S. patent application Ser. No. 11/536,642 filed Sep. 28, 2006, titled“Apparatus and Method for Stimulation of Nerves and Automated Control ofSurgical Instruments”;

U.S. Provisional Patent Application Ser. No. 60/872,930 filed Dec. 4,2006, titled “Apparatus and Method for Characterizing Optical SourcesUsed with Human and Animal Tissues”; and

U.S. patent application Ser. No. 11/948,912 filed Nov. 30, 2007, titled“Apparatus and Method for Characterizing Optical Sources Used with Humanand Animal Tissues”;

each of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates generally to tissue optics (interactions of lightwith human or animal tissue), and more particularly to methods andimplantable apparatus for stimulating nerves of the auditory system inanimals, for example, using an implantable device in medical treatmentsfor auditory, balance, and dizziness conditions of the vestibular systemusing laser light, such as infrared (IR) wavelengths, for opticalstimulation of nerves of the inner ear and related bodily systems.

BACKGROUND OF THE INVENTION

A person's inner ear includes the labyrinth, a delicate memberous systemof fluid passages that includes both the cochlea (which is part of theauditory system), and the vestibular system (which provides part of thesense of balance). The eyes also provide signals used for balance, as dojoint and muscle receptors and the cerebellum. The brain, specificallythe vestibular nuclear complex, receives and analyzes the informationfrom these systems, and generates signals that control a person'sbalance.

Each inner-ear includes three semicircular canals and a vestibule, theregion where the semicircular canals converge, and which is close to thecochlea (the hearing organ). The vestibular system also works with thevisual system to keep objects in focus when the head is moving.

Interference with, or infection, of the labyrinth can result in asyndrome of ailments called labyrinthitis. The symptoms of labrynthitisinclude temporary nausea, disorientation, vertigo, and dizziness.Labyrinthitis can be caused by viral infections, bacterial infections,physical blockage of the inner ear, or due to decompression sickness.

Some people lose vestibular hair cells or suffer from balance anddizziness problems that are not readily treatable through therapy and/ordrugs. These conditions can be very debilitating, since the affectedperson must remain still to minimize unpleasant dizziness or feelingcontinuously “seasick.” The condition can also affect their ability towalk or keep their balance in general.

The semicircular canals in the inner ear form three loops that are fluidfilled and sense rotation of a person.

Otoliths (earstones) are small particles composed of calcium carbonatesupported in a gelatinous matrix in the viscous fluid of the saccule andutricle (the utricle is located in the vestibule, between thesemicircular canals and the cochlea within a swelling adjacent to thesemicircular canals, and the saccule is closer to the cochlea). Theinertia of these small particles (sometimes referred to as stones orcrystals) causes them to stimulate hair cells differently when the headmoves. The hair cells send signals down sensory nerve fibers via thevestibulocochlear cranial nerve (CN VIII), which are interpreted by thebrain as motion. The vestibular nucleus coordinates inputs from themuscles responsible for posture via the spinal cord, information oncontrol, balance, and movements via the cerebellum, and head and neckmovements via cranial nerves III, IV, and VI.

The saccule and utricle together make the otolith organs. They aresensitive to gravity and linear acceleration. Because of theirorientation in the head, the utricle is sensitive to a change inhorizontal movement, and the saccule gives information about verticalacceleration (such as when in an elevator). The otolith organs alsoprovide information to the brain orientation of the head, such as beingin a vertical position or prone position, or being face-up or face-down.

When the head is in a normal upright position, the otolith presses onthe sensory hair cell receptors. This pushes the hair cell processesdown and prevents them from moving side to side. However, when the headis tilted, the pull of gravity on statoconia shift the hair cellprocesses to the side, distorting them and sending a message to thecentral nervous system that the head is no longer level but now tilted.The motion sensation from the otoliths is involved in a large number ofreflexes. Damage to the otoliths or their central connections can impairocular and body stabilization.

U.S. Pat. No. 7,225,028 issued to Della Santina et al. on May 29, 2007,and titled “Dual Cochlear/Vestibular Stimulator with Control SignalsDerived from Motion and Speech Signals”, is incorporated herein byreference. Della Santina et al. describe a system for treating patientsaffected both by hearing loss and by balance disorders related tovestibular hypofunction and/or malfunction, which includes sensors ofsound and head movement, processing circuitry, a power source, and animplantable electrical stimulator capable of stimulating areas of thecochlea and areas of the vestibular system.

U.S. Patent Application Publication No. US 2007/0261127 A1 filed Jul.24, 2006 by Edward S. Boyden and Karl Deisseroth, titled“LIGHT-ACTIVATED CATION CHANNEL AND USES THEREOF”; U.S. PatentApplication Publication No. US 2007/0054319 A1 filed Jul. 24, 2006 byEdward S. Boyden and Karl Deisseroth, titled “LIGHT-ACTIVATED CATIONCHANNEL AND USES THEREOF” filed Jul. 24, 2006; and U.S. PatentApplication Publication No. US 2007/0053996 A1 filed Jul. 24, 2006 byEdward S. Boyden and Karl Deisseroth, titled “LIGHT-ACTIVATED CATIONCHANNEL AND USES THEREOF” are all incorporated herein by reference.These describe compositions and methods for light-activated cationchannel proteins and their uses within cell membranes and subcellularregions. They describe proteins, nucleic acids, vectors and methods forgenetically targeted expression of light-activated cation channels tospecific cells or defined cell populations. In particular thedescription provides millisecond-timescale temporal control of cationchannels using moderate light intensities in cells, cell lines,transgenic animals, and humans. The descriptions provide for opticallygenerating electrical spikes in nerve cells and other excitable cellsuseful for driving neuronal networks, drug screening, and therapy.

U.S. Pat. No. 6,748,275 issued to Lattner et al. on Jun. 8, 2004, andtitled “Vestibular Stimulation System and Method” (herein “Lattner etal. '275 patent”), is incorporated herein by reference. Lattner et al.'275 patent describes an apparatus and method in which the portions ofthe labyrinth associated with the labyrinthine sense and/or the nervesassociated therewith are stimulated to perform at least one of thefollowing functions: augment or control a patient's respiratoryfunction, open the patient's airway, induce sleep, and/or counteractvertigo. Solely as background, FIG. 1A and FIG. 1B are provided to showan environment for the present invention.

FIG. 1A is a perspective view of the labyrinth and associated nerves ofprior art embodiment for vestibular stimulation as described in theLattner et al. '275 patent. (See Lattner et al. '275 patent FIG. 7 andassociated written description). The Lattner et al. '275 patent (seecolumn 16, lines 13-45) describes augmenting the respiratory function byinducing stimulation of the vestibular nerve so that the polysynapticinteraction of the vestibular nerve with the nerves associated withrespiration can augment the patient's respiratory function. Stimulationof the vestibular nerve is accomplished by stimulating vestibular nerve42 directly and/or by stimulating one or more of nerve branches 44 a and44 b. In one example, an electrode 82 in direct contact with vestibularnerve provides the stimulation to this nerve. A lead 84 couples theelectrode to the source of stimulation energy. Alternatively, or inaddition to electrode 82, Lattner et al. '275 contemplates providingelectrodes 86 b in contact with nerve branches 44 a and 44 b,respectively, to stimulate the nerve branches, which, in turn, inducestimulation in the vestibular nerve. Leads 54 b couple electrodes 86 bto the source of stimulation energy.

Lattner et al. '275 further describes that it is to be understood thatthe physiological function of augmenting the respiratory function ofthis embodiment of Lattner et al. '275 contemplates stimulating portionsof the vestibular system before the vestibular nerve or nerve branchesto induce a neural transmission therein. Thus, this embodiment ofLattner et al. '275 also contemplates stimulating the structures of thevestibular system, such as the semicircular canals 46 a, ampullae 46 b,utricle 46 c, saccule 46 d, and common membranous limb 46 e using any ofthe described stimulation mechanisms. In addition, Lattner et al. '275contemplates globally stimulating the vestibular area in synchronizationwith breathing to augment the patient's respiratory function.

FIG. 1B is a perspective view of the labyrinth and associated nerves ofprior art alternative embodiment for vestibular stimulation as describedin the '275 patent to Lattner et al. (See Lattner et al. '275 patentFIG. 8 and associated written description). Lattner et al. '275 (seecolumn 16, lines 13-45) describes that, in one embodiment, the sensationof rocking is induced by stimulating one or more of the semicircularcanals, saccules, and/or utricles. The Lattner et al. '275 FIG. 1Bexample illustrates vestibular nerve 42, branch nerves 44, andvestibular ganglion 41. Also illustrated are first stimulation element88 provided at a first location on semicircular canal 90, and a secondstimulation element 92 provided at a second location on the samesemicircular canal. The first and second stimulation elements 88 and 92are operatively coupled to a signal receiving device for controlling theapplication of stimulation to semicircular canal 90. In one Lattner etal. '275 embodiment, stimulation elements 88 and 92 are electrodes, suchas cuff electrodes, for providing electrical energy to the patient froma source. Leads 94 and 96 couple the electrodes to the power supply.

Lattner et al. '275 describes in another embodiment, first and secondstimulation elements 88 and 92 are pressure-application devices, such asthe pressure cuffs, that apply a pressure to the semicircular canal. Inwhich case, leads 94 and 96 are conduits for carrying an inflating fluidto the pressure cuffs. In yet another Lattner et al. '275 embodiment,first and second stimulation elements 88 and 92 are pressure applicationdevices located within the semicircular canal for moving the fluidcontained therein. In still another embodiment of Lattner et al. '275,stimulation of the canals is accomplished via one or more vibratingelements located proximate to the semicircular canal, such as in thebone tissue adjacent the duct in which the semicircular canal islocated.

In this embodiment of Lattner et al. '275, a rocking sensation isinduced in the patient by alternatively actuating first and secondstimulation elements 88 and 92. For example, if first and secondstimulation elements 88 and 92 are pressure cuffs, first stimulationelement 88 is actuated and second stimulation element 92 is deactivatedto tend to urge the fluid within semicircular canal 90 in a firstdirection toward the second stimulation element, as indicated by arrowB. Thereafter, first stimulation element 88 is deactivated and secondstimulation element 92 is actuated to urge the fluid in the oppositedirection back toward the first stimulation element, as indicated byarrow C. This process is repeated to move the fluid back and forthwithin the semicircular canal, which is the same effect that takes placewhen the person is physically rocked. Lattner et al. '275 describes thefrequency of the back and forth movement of the fluid can be altered tochange the rocking speed of the patient.

Lattner et al. '275 describes that the placement of first and secondstimulation element 88 and 92 on semicircular canal 90, which is theposterior semicircular canal, may not be the optimum location for allpatients, so Lattner et al. '275 contemplates locating the first andsecond stimulation element on other semicircular canals, such asanterior semicircular canal 98 and/or lateral semicircular canal 100.Lattner et al. '275 describes that such stimulation elements can beprovided at one or more of these semicircular canals, which isespecially important given the three-dimensional nature of the humanbalancing system. Lattner et al. '275 further describes that the numberof stimulation elements and their specific location on the associatedsemicircular canals is also subject to variation so long as theactuation of these stimulation elements produces a rocking sensation inthe patient.

In another embodiment of Lattner et al. '275, the stimulation elementsare provided at ampullae 102, saccule 104, and/or utricle 106 ratherthan on, in or adjacent to the semicircular canals. Lattner et al. '275contemplates using the stimulation techniques discussed to alternativelystimulate these structures to create a rocking sensation.

In contrast, the present invention is directed to stimulation of thevestibular organs to improve balance and/or treat other conditions.

U.S. Pat. No. 7,004,645 issued to Lemoff et al. on Feb. 28, 2006, andtitled “VCSEL array configuration for a parallel WDM transmitter”, isincorporated herein by reference. Lemoff et al. describe VCSEL arrayconfigurations. Transmitters that use several wavelengths of VCSELs arebuilt up out of multiple die (e.g., ones having two-dimensionalsingle-wavelength monolithic VCSEL arrays) to avoid the difficulty ofmanufacturing monolithic arrays of VCSELs with different opticalwavelengths. VCSEL configurations are laid out to insure that VCSELs ofdifferent wavelengths that destined for the same waveguide are closetogether.

U.S. Pat. No. 7,116,886 issued to Colgan et al. on Oct. 3, 2006, andtitled “Devices and methods for side-coupling optical fibers tooptoelectronic components”, is incorporated herein by reference. Colganet al. describe optical devices and methods for mounting optical fibersand for side-coupling light between optical fibers and VCSEL arraysusing a modified silicon V-groove, or silicon V-groove array, whereinV-grooves, which are designed for precisely aligning/spacing opticalfibers, are “recessed” below the surface of the silicon. Optical fiberscan be recessed below the surface of the silicon substrate such that aprecisely controlled portion of the cladding layer extending above thesilicon surface can be removed (lapped). With the cladding layerremoved, the separation between the fiber core(s) and optoelectronicdevice(s) can be reduced resulting in improved optical coupling when theoptical fiber silicon array is connected to, e.g., a VCSEL array.

U.S. Pat. No. 7,031,363 issued to Biard et al. on Apr. 18, 2006, andtitled “Long wavelength VCSEL device processing”, is incorporated hereinby reference. Biard et al. describe a process for making a laserstructure such as a vertical cavity surface emitting laser (VCSEL). TheVCSEL designs described include those applicable to the 1200 to 1800 nmwavelength range

U.S. Pat. No. 6,546,291 issued to Merfeld et al. on Apr. 8, 2003, andtitled “Balance Prosthesis”, is incorporated herein by reference.Merfeld et al. describe a wearable balance prosthesis that providesinformation indicative of a wearer's spatial orientation. The balanceprosthesis includes a motion-sensing system to be worn by the wearer anda signal processor in communication with the motion-sensing system. Thesignal processor provides an orientation signal to an encoder. Theencoder generates a feedback signal on the basis of the estimate of thespatial orientation provides that signal to a stimulator coupled to thewearer's nervous system.

Vestibular problems in the inner ear, the semicircular canal organs orthe otolith organs can cause very debilitating conditions, includingdizziness and vertigo. Improved apparatus and methods are needed totreat various vestibular problems.

BRIEF SUMMARY OF THE INVENTION

The present invention includes a vestibular implant to deliver optical(e.g., using infrared light from a laser) stimulation of vestibularnerves in order to restore the vestibular function and improve balanceand/or avoid dizziness or improve other functions of the vestibularsystem (i.e., eye movements, posture, gait, sleep, etc). Theinfrared-light nerve-stimulation technique is significant since, unlikeelectrical nerve stimulation, the light can selectively stimulatecertain vestibular nerves without simultaneously spreading thestimulation to other sets of vestibular nerves. In some embodiments, thedevice has as few as five (5) channels to control the three (3)rotational vestibular sensors (i.e., to stimulate nerves of thesemicircular canals) and the two (2) linear vestibular sensors (i.e., tostimulate nerves of the otolith organs—the utricle and saccule). In someembodiments, the device has as few as one (1) channel to control asingle malfunctioning vestibular organ such as one of the three (3)rotational vestibular sensors (i.e., to stimulate nerves of thesemicircular canals) or one of the two (2) linear vestibular sensors(i.e., to stimulate nerves of the otolith organs—the utricle orsaccule). In some other embodiments, numerous channels are implanted tostimulate the vestibular sensors and/or nerves. Optical stimulators areadvantageous in that a large number of stimulators can be combined intoa small cross-sectional area, e.g., an optical fiber bundle, or avertical-cavity surface-emitting-laser (VCSEL) array or other optimizedand compact light source. Using a large number of optical stimulatorsprovides easier implantation due to less critical placement of thesimulators, and later testing of the implanted stimulators can determinewhich stimulators are most effective for stimulating the desirednerve(s) and treating the desired condition. In addition, in someembodiments, the technique of varying the wavelength is used to controlthe penetration depth of the nerve stimulator, which is used toexternally stimulate the vestibular organs without having to physicallypenetrate the organs. In some embodiments, the optical stimulator isplaced external to the organ and provides optical stimulation to thenerves from the organ, instead of implanting a probe (e.g., anelectrical probe) internal to the organ. This is advantageous in that aless invasive surgery can be used. Further, an implantable device heldwithin the patient's body reduces the risk of infections and othercomplications. In some embodiments, optical nerve stimulation ispropagated through at least some amount of bone. In some otherembodiments, a small hole is made into or through the bone of the skullto permit optical stimulation to the target nerves. In some embodiments,the Cranial Nerve VIII (CN VIII)—also called the vestibulocochlearnerve—is stimulated by a prosthetic device of the present invention.Some embodiments provide a vestibular prosthesis that uses surfacestimulation or intrafascicular stimulation (i.e., located or occurringwithin a vascular bundle; e.g., some embodiments embed the optical (orelectro-optical) probe fiber(s) under the collagenous layers of nerveand situate the stimulation probe on the excitable axonal layer).

In some embodiments, various laser technologies are used to provide theoptical nerve stimulation. In some embodiments, a semiconductor diodelaser is used. In some embodiments, a fiber laser is used. In someembodiments, a vertical-cavity surface-emitting-laser (VCSEL) arraystimulator apparatus is used to provide optical nerve stimulation. Insome embodiments, the laser light is delivered to the stimulation siteusing an optical fiber.

As used herein, a probe is the optical delivery device. In someembodiments, various probe designs are used to deliver opticalstimulation to the desired area. In some embodiments, an end-emitting isused, while in other embodiments, an edge-emitting probe is used. Insome embodiments, the probe has a broad emission if a large arearequires activation. In some embodiments, a grating or lens in anoptical fiber is used to provide a broad emission area.

In some embodiments, the optical stimulator (e.g., VCSEL array) isimplanted locally or proximally to the nerves to be stimulated. In someother embodiments, the optical stimulators are remotely located and areoperatively connected using optical fibers with one end implantedproximal to the nerves to be stimulated. In some other embodiments, theoptical stimulators are remotely located outside the body and areoperatively connected through the skin using optical fibers with one endimplanted proximal to the nerves to be stimulated. In some embodiments alens or set of lenses is used to shape the beam and direct light fromthe source directly to the excitable tissues.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of the labyrinth and associated nerves ofprior art embodiment for vestibular stimulation.

FIG. 1B is a perspective view of the labyrinth and associated nerves ofprior art alternative embodiment for vestibular stimulation.

FIG. 2 is a perspective view of an inner-ear labyrinth vestibular nervesand organs 200.

FIG. 3 is a perspective view of an inner-ear labyrinth and oneembodiment of the present invention using optical sources and opticalfiber(s) to provide optical stimulation to vestibular nerves.

FIG. 3.1 is a perspective view of a conventional optical fiber arrayconnector head 301 that is used for some embodiments of optical head330.

FIG. 4 is a perspective view of an inner-ear labyrinth and oneembodiment of the present invention using a VCSEL controller and VCSELarray to provide optical stimulation to vestibular nerves.

FIG. 4.1 shows a conceptual view of an embodiment in accordance with theinvention.

FIG. 4.2 shows an embodiment of a VCSEL array configuration 402 for aparallel wavelength-division transmitter in accordance with theinvention.

FIG. 4.3 shows a simplified view of solder bumps 4199 and 4599 on thebottoms of die 4121 and die 4515, respectively.

FIG. 5 is a block diagram of an implantable system 500 that uses a VCSELarray for light stimulation of vestibular nerves and/or organs 200.

FIG. 6 is a schematic 600 detailing an implantable version of a devicethat is powered and controlled via an external source.

FIG. 7 is a block diagram of a light-delivery device 700 using amanually controlled selector 704 and delivery system 710 of laser light.

DETAILED DESCRIPTION OF THE INVENTION

Although the following detailed description contains many specifics forthe purpose of illustration, a person of ordinary skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the invention. Accordingly, the followingpreferred embodiments of the invention are set forth without any loss ofgenerality to, and without imposing limitations upon the claimedinvention. Further, in the following detailed description of thepreferred embodiments, reference is made to the accompanying drawingsthat form a part hereof, and in which are shown by way of illustrationspecific embodiments in which the invention may be practiced. It isunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

The leading digit(s) of reference numbers appearing in the Figuresgenerally corresponds to the Figure number in which that component isfirst introduced, such that the same reference number is used throughoutto refer to an identical component which appears in multiple Figures.Signals and connections may be referred to by the same reference numberor label, and the actual meaning will be clear from its use in thecontext of the description.

As used herein, the inner-ear vestibular organs (or vestibular organs)are defined as including the saccule and utricle otolith organs and thesemicircular canal organs. As used herein, optical nerve stimulation isdefined as the direct stimulation of nerves or nerve endings by means oflaser light. Optical nerve stimulation includes optically stimulatingnerves and especially optically stimulating in order to generate oralter one or more nerve action potentials (NAPs). Altering a nerveaction potential includes preventing a nerve action potential (NAP) thatwould otherwise occur and/or altering the frequency of NAPs. Compoundnerve action potential (CNAP) is one form of nerve action potential(NAP). As used herein, optical nerve stimulation is not limited tostimulation of the optic nerve or retina tissues (which are related tothe eye and sight). Rather, optical stimulation can be used forgenerating a nerve signal on virtually any nerve, since any nerve orother similar excitable tissue can be optically stimulated (whichgenerates a short temperature transient) such that the nerve generates anerve action potential based on the laser-tissue interaction leading toa stimulatory effect.

In some embodiments, the invention provides an optical nerve stimulationdevice and method that provides different nerve stimulation signals to aplurality of different vestibular nerves, including at least some of thethree semicircular canal nerves and/or the two otolith organ nerves. Insome embodiments, balance conditions of the person are sensed by, ortransmitted to, the implanted device, and based on the device-sensedbalance conditions, controlled and varying optical nerve-stimulationsignals are sent to a plurality of the different vestibular nerves.

An afferent nerve carries impulses (i.e., nerve action potentials)toward the central nervous system. The opposite of afferent is efferent,wherein efferent nerves carry impulses (i.e., nerve action potentials)from the central nervous system, typically to control or actuatemuscles, effector organs, or glands. For at least some vestibularorgans, the afferent nerves from vestibular sense organ(s) are in pairs(one on each side of the head—i.e., right and left), and when inbalance, both nerves send nerve pulses at equal rates (e.g., 50 pulsesper second from one of the pair of nerves and 50 pulses per second fromthe other), but when out of balance, send nerve pulses at differentrates (e.g., 10 pulses per second from one of the pair of nerves and 90pulses per second from the other). Thus, too few nerve pulses or toomany nerve pulses can both cause a sense of imbalance. Some embodimentsof the present invention provide optical nerve stimulation to cause morepulses per second to be transmitted. Some embodiments of the presentinvention optionally provide different optical nerve stimulation tocause fewer pulses per second to be transmitted. In some embodiments,the present invention provides an implanted stimulation device thatprovides vestibular stimulation to only a single side, while otherembodiments provide controlled vestibular stimulation to vestibularorgans on both left and right sides of a person, which can be stimulatedindependently, or stimulated simultaneously but at different pulse ratesin order, for example, to achieve controlled differential stimulation toobtain a better sense of balance, or by other simultaneous signals toachieve a desired sensation for the patient.

FIG. 2 is a perspective view of an inner-ear labyrinth vestibular nervesand organs 200. The vestibular nerve 110 is an afferent nerve thatcarries impulses toward the central nervous system. The vestibular nervebranches 125 (including the anterior canal nerve, the posterior canalnerve, the lateral canal nerve, the utricular nerve, and the saccularnerve) join together at the vestibular ganglion 120. The vestibularlabyrinth includes the anterior semicircular canal 151 and anteriorsemicircular ampulla 161, lateral semicircular canal 152 and lateralsemicircular ampulla 162, posterior semicircular canal 153 and posteriorsemicircular ampulla 163, the utricle 140, and the saccule 130. Thecochlear labyrinth includes the cochlea 180 and the cochlear nerve 170.

FIG. 3 is a perspective view of an inner-ear labyrinth and oneembodiment of the present invention using an optical signal source andoptical fiber to provide optical stimulation to vestibular nerves. Insome embodiments, an optical signal source 310 (such as a VCSEL array ora plurality of VCSEL sources) provides a plurality of light signals fromone or more laser light sources. Optical fiber bundle 320 carries thelight signals from the optical signal source 310 to the optical head330. The optical head 330 routes the optical fibers 340 of the opticalbundle 320 to a plurality of optical lenses 350. In the embodimentshown, the optical lenses 350 direct the light signals from the opticalsignal source 310 toward the vestibular nerve branches 125. In someother embodiments, the optical lenses 350 direct the light signals fromthe optical signal source 310 toward the vestibular nerve 110. In someother embodiments, the optical lenses direct the light signals from theoptical source 310 toward one or more nerves of the vestibular ampullae161, 162, 163, utricle 140, and the saccule 130.

In some embodiments, fiber-optic connection and delivery configurations,long-wavelength VCSEL devices, and VCSEL arrays, such as described inU.S. Pat. No. 7,116,886, U.S. Pat. No. 7,031,363 and U.S. Pat. No.7,004,645 (which are each incorporated herein by reference), are usedfor the optical fiber bundle 320 and optical signal source 310.

FIG. 3.1 is a perspective view of a conventional optical fiber arrayconnector head 301 that is used for some embodiments of optical head330. The connector 301 comprises two plates 311 and 312 (e.g., siliconplates) each having an array of optical fiber support channels 311 a,312 a (V-grooves) formed on interior surfaces thereof, corresponding toa longitudinal direction of optical fibers to be mounted therein. Aplurality of optical fibers 313 are secured in corresponding channels311 a, 312 a, between the plates 311, 312 using known clamping andbonding methods. The FIG. 3.1 shows that the light-emitting front face319 is planar and the light is emitted in substantially paralleldirections from the plurality of fibers 313 at that front face 319.

In general, an optical-fiber-connector head such as shown in FIG. 3.1based on a silicon V-groove array is formed by: (1) etching V-groovechannels into a silicon substrate and dicing silicon plates (having thechannels) out from the wafer; (2) bonding the optical fiber(s) betweencorresponding V-grooves of top and bottom plates; and then (3) grindingand polishing the mating end of the connector so that the ends of theoptical fiber(s) are coplanar with the front face 319 at the front edgesof the V-groove plates 311, 312. For an optical-fiber-connector headthat will not be permanently joined with an index matching material, itis desirable to have the optical fibers project slightly beyond theedges of the V-groove plates to ensure that there is no gap between theconnected optical fibers. Silicon V-channel arrays are preferablyemployed for forming silicon spacing chips and connectors such as shownin FIG. 3.1 because the silicon v-groove arrays can be readilyfabricated with high precision via anisotropic etching of singlecrystalline silicon. More specifically, the formation of V-grooves insilicon is based on knowledge that the crystal of the silicon wafer hasdifferent atomic densities-per-unit-area on different surfaces (siliconcrystal-lattice orientations commonly known as 100, 110, 111) of thecrystal lattice, and that the etching rates vary along the differentdirections of the crystal lattice. Further, silicon is a very rigidmaterial with a low thermal coefficient of expansion, which propertiesrender silicon ideal for mounting optical fibers.

FIG. 4 is a perspective view of an inner-ear labyrinth and oneembodiment of the present invention using a VCSEL controller and VCSELarray to provide optical stimulation to vestibular nerves. In someembodiments, a VCSEL controller 410 provides a plurality of electricalsignals and is operatively connected to the VCSEL array head 430 throughelectrical bundle 420. The electrical signals drive a VCSEL array head430 implanted near the vestibular organs producing light signals. TheVCSEL array head 430 produces a plurality of laser light signals. Insome embodiments, the VCSEL array head 430 contains a plurality ofoptical lenses 450 to direct the laser light on to the nerves and/ortissue. In the embodiment shown, the optical lenses 450 direct the lightsignals from the VCSEL array head 440 toward the vestibular nervebranches 125. In some other embodiments, the optical lenses 450 directthe light signals from the VCSEL array head 430 toward the vestibularnerve 110. In some other embodiments, the optical lenses direct thelight signals from the VCSEL array head 440 toward one or more nerves ofthe vestibular ampullae 161, 162, 163, utricle 140, and the saccule 130.

In some embodiments, long-wavelength VCSEL devices and/or VCSEL arrays,such as described in U.S. Pat. No. 7,031,363 and U.S. Pat. No. 7,004,645(which are each incorporated herein by reference), are used for theVCSEL array head 440 in FIG. 4.

In accordance with the invention, a configuration of VCSELs may bearranged as linear arrays, N-by-N arrays or other geometries inaccordance with the invention. FIG. 4.1 shows a conceptual view of anembodiment in accordance with the invention. In some embodiments, eachof the VCSELs 4100, 4200, 4300, 4400 operates at a separate wavelengthto generate light beams 460, 461, 462, 463, each light beam being at aparticular wavelength. Filterless parallel wavelength-divisionmultiplexer element 401 is used to direct light, from VCSELconfiguration 470, comprising VCSELs 4100, 4200, 4300, 4400, to thedestination target 425. The number of VCSELs and lenses may be increasedalong with the number of optical targets. Using two or more filterlessparallel wavelength-division multiplexer elements 401 with two or moreoptical destination targets, respectively, results in a filterlessparallel wavelength-division multiplexer.

Lenses in plane 4001, such as lenses 411, 421, 431, 441, are typicallymade just large enough to collect most of the light emitted by VCSELs4100, 4200, 4300, 4400 such as beams 460, 461, 462, 463, respectively.The general design considerations are as follows. Because a VCSELtypically emits a vertical cone of light, the center of the lensaperture in plane 4001 should be aligned with the VCSEL aperture tocapture the VCSEL light. In order to direct light from a first lens in afirst plane to the appropriate lens in a second plane, the vertex of thefirst lens must lie on the line connecting the VCSEL aperture to thecenter of the appropriate lens aperture in the second plane. Thisresults in an offset between the center of the first lens aperture andthe vertex of the first lens. Therefore, the first lens is an off-axissection of a lens. The appropriate lens in the second plane needs to belarge enough to capture most of the light incident on it and focus thislight into the optical destination target. The lens in the second planefocuses the incident light into the optical fiber which is positioned tominimize the overall range of angles of the incident light going intothe optical destination target. Because the lens in the second planeneeds to focus the incident into the optical destination target, theline connecting the optical destination target center with the lensvertex needs to be parallel to the incident light which by design isparallel to the line connecting the VCSEL aperture to the center of thelens in second plane. This requires that there be an offset between thecenter of the lens aperture in the second plane and the lens vertex.Hence, the lens in second plane is also off-axis. The other lenses ofthe multiplexer and any additional optical destination targets aresimilarly positioned.

The general design considerations discussed above assume that the VCSELis a point source, which is an approximation. Additional assumptionshave neglected diffraction and lens aberrations. The designimplementation of wavelength-division multiplexer 401 corrects for thesefactors and the implementation typically will differ from the abovedescription that, however, results in a baseline design that isqualitatively similar to the actual implementation. In practice, thequalitative description provides a starting configuration that may beiteratively modified using ray-tracing software packages such as ZEMAX®or CODE V® until the amount of VCSEL light reaching the optical fiberhas been optimized.

With respect to FIG. 4.1, for example, VCSEL 4100 is lined up with thecenter of lens 411, and lens 411 needs to be large enough to capturemost of the light from VCSEL 4100. The vertex of lens 411 lies in plane4001 on the line defined by VCSEL 4100 and the center of lens 412.Hence, the vertex of lens 411 and the center of the aperture of lens 411are offset from each other and lens 411 is an off-axis lens. Lens 412 inplane 4002 needs to be sufficiently large to collect most of the lightincident on it and focus that light into destination target 425. Lens412 focuses most of the incident light into destination target 425 whichis positioned to minimize the overall range of angles of the incidentlight that is entering destination target 425. Because lens 412 focusesthe light into destination target 425, the line connecting the center ofdestination target 425 needs to be parallel to the incident light. Bydesign, the incident light is parallel to the line connecting theaperture of VCSEL 4100 to the center of lens 412 in plane 4002. Thisrequires that the vertex of lens 412 and the center of the aperture oflens 412 are offset from each other. Hence, lens 412 is also an off-axislens. Similar considerations apply for lenses 421, 431, 441 in plane4001 and lenses 422, 432, 442 in plane 4002.

As described above, in some embodiments, each of VCSELs 4100, 4200,4300, 4400 operates at a separate wavelength to generate light beams460, 461, 462, 463, each light beam being at a particular wavelength.VCSELs 4100, 4200, 4300, 4400 typically reside on separate die. Lightbeams 460, 461, 462, 463 enter filterless parallel wavelength-divisionmultiplexer 401 having two planes of lenses. In FIG. 4.1, VCSELs 4100,4200, 4300, 4400 transmit light beams 460, 461, 462, 463 to lenses 411,421, 431, 441 residing in first lens plane 4001. Lenses 411, 421, 431,441 function to redirect beams 460, 461, 462, 463 into lenses 412, 422,432, 442, respectively. Lenses 412, 422, 432, 442 residing in secondlens plane 4002 function to direct light beams 460, 461, 462, 463,respectively, into destination target 425. Hence, light of fourdifferent wavelengths is multiplexed into destination target 425.

FIG. 4.2 shows an embodiment of a VCSEL array configuration 402 for aparallel wavelength-division transmitter in accordance with theinvention. Configuration 402 shown in FIG. 4.2 is a four-wavelength,twelve-destination-target configuration constructed from two-dimensionalsingle-wavelength monolithic VCSEL arrays. In this embodiment, there arethree groups 4101, 4102, 4103 of four square dies 4121, 4122, 4123, 4124corresponding to two-by-two VCSEL arrays 4150, 4160, 4170, 4180,respectively. The number of dies and groups in the configuration may beincreased in accordance with the invention to allow for both morewavelengths and destination targets. VCSEL arrays 4150, 4160, 4170, 4180each operate at a different wavelength. Dies 4121, 4122, 4123, 4124 arearranged such that each group 4101, 4102, 4103 contains VCSEL arrays foreach of the four wavelengths. This arrangement ensures that devices ofdifferent wavelengths are sufficiently close together to avoid the needfor large angle deflections within multiplexer element 401 (i.e.,between planes 4001 and 4002) to direct the light beams into eachrespective destination target 425. The need for large angle deflectionsusing refractive lenses presents a cost issue and using diffractivelenses results in higher light losses.

The substantially square aspect ratio of dies 4121, 4122, 4123, 4124improves handle-ability in the manufacturing environment and reduceshandling breakage. VCSEL material is typically brittle and VCSELstructures with a high aspect ratio are inherently more susceptible todamage than VCSEL structures with a low aspect ratio. Long VCSEL arrays(high aspect ratio) have proportionally more surface area than squareVCSEL arrays (low aspect ratio). For example, a three-by-three VCSELarray on a 250-μm pitch has nine devices with a perimeter of 3000 μmwhereas a one-by-nine VCSEL array also has nine devices but for the samepitch has a 5000-μm perimeter. Because cracks usually start on the dieperimeter, reducing the die perimeter typically increases theVCSEL-array yield. Additionally, long VCSEL arrays are typically subjectto more stress due to thermally induced stresses resulting fromattachment to the substrate material.

Conventional production tooling is typically designed to handle partsthat have a low aspect ratio. The majority of semiconductor devices havea relatively low aspect ratio (typically an approximately square shapewhen viewed from the top or bottom) and as a result, the conventionalproduction tooling is typically designed to accommodate such low aspectratio shapes.

Using two-by-two VCSEL arrays 4150, 4160, 4170, 4180 located on dies4121, 4122, 4123, 4124, respectively, the arrangement of the bond-pads(not shown) on each die 4121, 4122, 4123, 4124 allows the use ofsolder-reflow self alignment during alignment and attachment, decreasingassembly costs. Typically, solder-reflow self alignment is moreeffective for two-by-two arrays such as VCSEL arrays 4150, 4160, 4170,4180.

FIG. 4.3 shows a simplified view of solder bumps 4199 and 4599 on thebottoms of die 4121 and die 4515, respectively. Solder bumps 4199 and4599 act to self align die 4121 and die 4515, respectively, duringreflow.

The self-alignment mechanism is due to minimization of the surfacetension at each of the individual solder attachment sites so that ateach solder attachment site the surface tension is minimized. Eachsolder bump has a somewhat different volume and wets the bonding padssomewhat differently. The differences are relatively small but causeeach solder bump to pull dies 4121 and 4515 in a different direction. Avector summing of the various forces occurs resulting in the finalpositioning of die 4121 and 4515. Because a two-by-two VCSEL array has ahigher degree of symmetry than a one-by-twelve VCSEL array, betteralignment typically results for a two-by-two VCSEL array or other VCSELarrays having a higher degree of symmetry than a one-by-twelve arrayVCSEL array.

The size of two-by-two VCSEL arrays 4150, 4160, 4170, 4180 can bereduced in size to the minimum size needed for solder bumps to attachVCSEL arrays 4150, 4160, 4170, 4180 to the substrate. For example, ifsufficiently small solder bumps are used to attach two-by-two VCSELarrays 4150, 4160, 4170, 1480 that are 150 μm on a side, the VCSEL arraysize will work with filterless parallel wavelength-division multiplexereven if the pitch of the optical fiber array is 250 μm. In contrast, forone-by-twelve VCSEL arrays, the pitch of the VCSEL array is constrainedby and must match the pitch of the optical fiber array. Because the costof VCSEL die is proportional to their area cost may be reduced byreducing area. In addition, having a relatively small number of devicesper die increases the yield per die. For example, if 5% of the VCSELs ina one-by-twelve VCSEL arrays are defective, the array yield will beabout 54% if the defects are random. For two-by-two VCSEL arrays 4150,4160, 4170, 4180 with the same defect rate of 5%, the array yield willbe 81%. Because yield per die is proportional to cost, smaller arraysare much cheaper.

FIG. 5 is a block diagram of an implantable/partially implantable system500 that uses a VCSEL array for light stimulation of vestibular nervesand/or organs 200 (e.g., some embodiments use a VCSEL array such asdescribed by U.S. Provisional Patent Application No. 60/964,634 filedAug. 13, 2007, titled “VCSEL Array Stimulator Apparatus and Method forLight Stimulation of Bodily Tissues”). System 500 represents oneembodiment of the present invention, wherein a low-power, low-thresholdVCSEL array 501 emits laser light from each of a plurality of VCSELs,for example VCSELs implemented as an array of separately activatablelasers formed in a monolithic semiconductor chip. Each laser beam isseparately controlled by laser-and-power controller 510 that drives thelaser-diode VCSELs under control of a processor or circuitry 509 thatgenerates signals that are configured to stimulate the tissue asdesired. For example, in some embodiments, the light signals 505 arecollimated, focused and/or guided by optics 503. In some embodiments,the system uses a visible laser and/or LED array 502 that producevisible light signals 512 to help align the VCSEL laser array signals511 with the lens array/beam coupler/combiner optics 503.

In some embodiments, long-wavelength VCSEL devices and/or VCSEL arrays,such as described in U.S. Pat. No. 7,031,363 and U.S. Pat. No. 7,004,645(which are each incorporated herein by reference), are used for theVCSEL array 501.

With VCSEL emitters as small as about ten (10) microns (or smaller) indiameter per channel, in some embodiments, a single VCSEL chip orassembly is used to output multiple independent stimulation channels(VCSEL laser signals) in any array permutation or shape, and in someembodiments, these channels are fiber coupled and/or direct lightstraight to a plurality of areas of tissue. In some embodiments, acombination of both fiber-coupled and direct propagation laser output isused to stimulate tissue.

FIG. 6 is a schematic 600 detailing an implantable version of a devicethat is powered and controlled via an external source. In someembodiments, an optical stimulator 601 is implanted into a subject(e.g., a patient) 99 to provide an efficacious amount of IR-lightstimulation to a nerve fiber. In some embodiments, this opticalstimulator 601 contains components including an RF recharger 606,battery 607, controller 608, visible-laser source 609, IR-laser source610 and combiner 611, with each being operatively coupled to each othersuch that the RF recharger 606 provides electrical power to the battery607, which, in turn powers the controller 608. The controller 608provides electrical power and control signals to the visible-lasersource 609 and IR-laser source 610, regulating type and intensity ofpulse generated by each of these sources. In some embodiments, the lightfrom these sources (i.e., 609 and 610) is sent to a combiner 611 wherethe light is combined into a single beam. In some embodiments, thecombiner 611 is operatively coupled to an optical-fiber structure 602that is then positioned such that it can deliver an efficacious amountof IR light to a point of stimulation 603. In some embodiments, thispoint may be nerve fibers located along the spinal cord, whereas inother embodiments this point of stimulation 603 may be some other groupof nerve fibers. As with other embodiments, light from the visible-lasersource 609 is used to position the optical-fiber structure 602 relativeto a point of stimulation 603. Once the optical-fiber structure 602 ispositioned, IR laser light may be applied.

In at least one embodiment, control of the optical stimulator 601 is viaa radio remote programmer 604 that sends control signals to theabove-described controller 608. In some embodiments, an RF charge source605 is used to supply electrical power to the optical stimulator 601.

In some embodiments, a plurality of light-emitting optical-fiberstructures is used to emit efficacious IR and/or visible light tostimulate nerve tissue. In at least one embodiment, the tips of theseoptical-fiber structures are arranged in an array-type pattern, whereasin other embodiments the tips are arranged in a matrix-type pattern.Other patterns are also provided and are only limited by empiricaltesting and/or modeling to determine which patterns are more or lesseffective.

In some embodiments, in those instances where an array- or matrix-typeconfiguration is used software is used to isolate an isomorphism betweena particular light-emitting optical-fiber structure and certain nervetissues. Put another way, once a reaction of a particular nerve tissueis determined, software can be used to determine which light-emittingoptical-fiber structure actually caused the reaction on the part of thenerve tissue. The algorithm to determine which light-emitting structurecaused a reaction could be a simple sequential-search algorithm wherebyeach light-emitting optical-fiber structure individually emits light byitself and a nerve-tissue reaction is determined to be present orabsent, or it could be a more sophisticated binary-search algorithmwhereby, for example, an array of light-emitting optical-fiberstructures is divided in half, each sub-array tested individually todetermine whether a nerve-tissue reaction is present or absent, and ifone sub-array is indeed associated with a nerve-tissue reaction thenthat sub-array is again divided in half and the process repeated. Someembodiments use algorithms to search array-like structures and matrices,such as are well known in the art. (See Algorithms in C++: Parts 1-43^(rd) Edition, by Robert Sedgewick, Addison Wesley 1998.)

FIG. 7 is a block diagram of a light-delivery device 700 using amanually controlled selector 704 and delivery system 710 of laser light.In some embodiments, delivery system 710 includes a multi-fiber ferrule705 presenting a plurality of optical-fiber-structure ends 707 closelyspaced apart along a line and placed into a delivery head 701. Fiberbundle 706 includes a plurality of fibers that, in some embodiments, areeach separately controllable to selectively deliver stimulation lightsignals to one or more of the plurality of optical-fiber-structure ends707.

In some cases, for each fiber in bundle 706 a single-emitter diode witha single-mode fiber is used, depending on the nerve size. In someembodiments, the head 701 is placed across a nerve bundle within whichthe desired nerve of interest is located. Individual optical fibers offiber bundle 706 are illuminated with stimulation light successively, inorder to locate a particular nerve of interest. This allows the user tomove the light beam small distances between adjacent nerves withoutmoving the delivery head or having to manually adjust small distances byhand. In some embodiments, a foot control having the same functionalityis used in place of button or lever 704 and selector wheel 709, in orderthat small hand movements (as might be needed to actuate button 704) donot end up moving optical delivery head 701 relative to the nervebundle.

In some embodiments, nerve-stimulating IR light is emitted from the oneor more of the plurality of optical-fiber ends 707 in a successivesequence as controlled, e.g., through the depression of a button orlever 704 by the operator's finger 89, that controls movement ofratcheting selector wheel 709, which interrupts light passing fromlight-source fiber 717 to light-sensor fiber 718. In some embodiments,light-source fiber 717 and light-sensor fiber 718 are used to controldelivery of optical-nerve-stimulation light through the stimulationfiber 706. In some embodiments, the effectiveness of the IR-lightstimulation is determined by observing muscle twitches, through thepatient (or other subject) reporting a touch or other sensation, or by,for example, observing an fMRI image. In some embodiments, lightdelivered through fiber bundle 706 is controlled to sequentially scanthe light signal 799 across head 701.

In some embodiments, the pattern and speed of scanning is predeterminedby a computer program, while in other embodiments the pattern ismanually controlled by operator 89. In some embodiments, the computerprogram controls the emission of stimulation laser light in some type ofpattern based upon an algorithm (e.g., a programmed binary search,sequential search, or the like) so as to determine which optical-fiberend 707 delivered an efficacious dose of IR light to the nerve ofinterest. This allows placement of head 701 across a region of tissuethat contains the specific nerve of interest at some unknown position,and then scanning the position of the light output to the differentoptical-fiber ends 707 to locate the specific nerve without furthermovement of head 710. In some embodiments, the algorithm includes one ormore of the following: optically scanning a plurality of tissue areas,detecting a response of interest, and determining which of the scannedtissue areas, when optically stimulated, causes the response ofinterest. In some embodiments, the method further includes outputtingvisible light to point out a physical location of the scanned tissuesthat caused the response of interest (e.g., shining a laser light outthe one fiber end 707 that would illuminate the selected nerve). In someembodiments, the algorithm includes delivering different temporalpatterns and/or intensity profiles of one or more light pulses all to asingle location, and then repeating this for other locations. In someembodiments, the start and/or progression of the algorithm is operatorcontrolled (e.g., in some embodiments, a finger control such as controlmechanism 730 having one or more separately activable mechanisms (e.g.,buttons) 704 and one or more light-interrupter wheels 709, connected torespective optical control-signal fibers 717 and 718 of FIG. 7).

The actual reaction or response of nerve tissue to IR-light stimulationwould, in some embodiments, be determined through empirical observation(muscle twitches), subject reporting (of a touch sensation, tastesensation, or other sensation), by or some other method known in theart. In some embodiments, the user changes the position and/or function(e.g., changing the pulse length or intensity) of the handpiece on thebasis of the response. In other embodiments, the response is detected bythe stimulation system, and the function of the stimulation systemautomatically adjusts the stimulation based on the response feedback(e.g., in some embodiments, a stimulation signal is repeated until theresponse is detected, and then the stimulation stops and/or an audio orvisual indication of the response is output by the stimulation system).The manipulation of the array head itself is facilitated, in, at leastone embodiment, through the use of an ergonomically designed handle 712,which is covered by a replaceable, disposable, sterile sheath 711, andby the feedback to the user provided by having visible light deliveredto the area that would be stimulated by the IR stimulation signal and/orthe other audio and/or visual indications.

In some embodiments, light-delivery device 700 also includeslight-sensing capabilities in the same head configuration, wherein anoptical-nerve-stimulation light signal is sent out one or more of thefibers and a change in the appearance of the nerve or the surroundingtissue is sensed to determine whether or not the correct nerve wasselected by the stimulation signal. For example, in some embodiments, astimulation signal is sent out a first fiber and the fibers on eitherside are sensed (in the visible, UV and/or IR light spectrum) todetermine if the desired response occurred.

In other embodiments, light-delivery device 700 also includeslight-sensing capabilities in the same head configuration, wherein anobservation light signal (i.e., having one or more selected lightfrequencies) is sent out one or more of the fibers in bundle 706 (or, inother embodiments, ambient room illumination is used), and the color orthe appearance of the nerve or the surrounding tissue is sensed throughthat fiber end 707 or neighboring optical fibers to determine whetherthe location of tissue selected by the observation signal was nervetissue or other tissue based on differences in the color of thereflected light or other sensed. In some embodiments, a visible light issent out on one or more of the fibers in bundle 706 to illuminate andpoint out to the surgeon where the nerves are located (one or more ofthe fiber ends 707 would illuminate just the nerve tissue withoutilluminating other tissue).

In some embodiments, the present invention provides a method thatincludes obtaining a plurality of light signals from one or more laserlight sources; delivering the plurality of light signals to one or morenerves of each of one or more inner-ear vestibular organs of a livinganimal; and selectively controlling the plurality of light signals tooptically stimulate the one or more nerves in order to control nerveaction potentials (NAPS) produced by the one or more nerves.

In some embodiments, the living animal is a human person. In someembodiments, the living animal is a large non-human animal, e.g., a racehorse or dairy cow. In some embodiments, the living animal is a smallnon-human animal, e.g., a dog, cat, rodent or the like.

In some embodiments, the selectively controlling the light signalsincludes controlling a pulse width of the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling a duty cycle of the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling an on-time and an off-time of the plurality oflight signals.

In some embodiments, the selectively controlling the light signalsincludes controlling a wavelength of the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling a pulse repetition rate of the plurality of lightsignals.

In some embodiments, the selectively controlling the light signalsincludes controlling a pulse shape of the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling a minimum light intensity and a maximum lightintensity of the plurality of light signals.

In some embodiments, the present invention provides a combination ofelectrical and optical stimulation.

In some embodiments, the selectively controlling the light signalsincludes controlling a DC background amount of light intensity of theplurality of light signals.

In some embodiments, the present invention provides a combination ofelectrical and optical stimulation. In some embodiments, the methodfurther includes selectively controlling and applying to one or moretissues of the animal one or more electrical signals (i.e., hybridelectrical and optical stimulation of one or more tissues). In someembodiments, the selectively controlling and applying the electricalsignal(s) includes controlling and applying a DC background amount ofelectrical signal. In some embodiments, the selectively controlling andapplying the electrical signal(s) includes applying electrical pulses.

In some embodiments, the selectively controlling the light signalsincludes controlling a precharge amount of light intensity followed by atrigger amount of light intensity of the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling the light signals to delay at least some of theNAPs produced by the one or more nerves that would otherwise occurwithout the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling the light signals to increase a frequency of theNAPs produced by the one or more nerves that would otherwise occurwithout the plurality of light signals.

In some embodiments, the selectively controlling the light signalsincludes controlling the light signals to decrease a frequency of theNAPS produced by the one or more nerves that would otherwise occurwithout the plurality of light signals.

In some embodiments, the obtaining the plurality of light signalsincludes implanting a self-contained battery-poweredlaser-light-generation device.

In some embodiments, the plurality of light signals includes implantingself-contained infrared (IR) laser device.

In some embodiments, the delivering the plurality of light signals toone or more nerves of each of one or more inner-ear vestibular organsincludes using one or more optical fibers to guide the light signals.

In some embodiments, the delivering the plurality of light signals toone or more nerves of each of one or more inner-ear vestibular organsincludes positioning a delivery end of one or more fibers against avestibular organ and using the one or more optical fibers to guide thelight signals from a laser source to the vestibular organ.

In some embodiments, the one or more laser light sources include a firstlight source and a second light source, wherein the selectivelycontrolling the plurality of light signals includes controlling thefirst light source to send a first series of pulses during a firstperiod of time and controlling the second light source to send a secondseries of pulses during the first period of time, and wherein the firstseries of pulses differs from the second series of pulses in repetitionrate.

In some embodiments, the present invention provides a method furtherincluding sensing one or more conditions that affect balance, andwherein the selectively controlling the plurality of light signalsincludes controlling the light signals, at least partly based on thesensed one or more conditions that affect balance, to provide asense-of-balance nerve stimulation.

In some embodiments, the sensing of the one or more conditions thataffect balance includes sensing motion and orientation.

In some embodiments, the sensing the one or more conditions that affectbalance includes monitoring muscular stimulation.

In some embodiments, electrical stimulation delivered via nervesconnected to muscles is sensed. In some embodiments, the result of themuscular movement is sensed.

In some embodiments of the invention, monitoring muscular stimulationincludes monitoring eye movements.

In some embodiments, electrical stimulation delivered via nervesconnected to eye muscles is sensed. In some embodiments, the eyemovement is sensed to indirectly sense eye muscle stimulation.

In some embodiments, the present invention provides an apparatus thatincludes one or more laser light sources configured to generate aplurality of light signals; and a transmission medium configured totransmit the plurality of light signals from the one or more laser lightsources to one or more nerves of each of one or more inner-earvestibular organs of a living animal; a controller to selectivelycontrol the plurality of light signals from each of the one or moreinfrared-laser light sources such that the light signals providecontrolled optical stimulation to the one or more nerves in order tocontrol nerve action potentials (NAPS) produced by the one or morenerves.

In some embodiments, the living animal is a human person. In someembodiments, the living animal is a large non-human animal, e.g., a racehorse or dairy cow. In some embodiments, the living animal is a smallnon-human animal, e.g., a dog or cat.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a pulse width of the pluralityof light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a duty cycle of the pluralityof light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of an on-time and an off-time ofthe plurality of light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a wavelength of the pluralityof light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a pulse repetition rate of theplurality of light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a pulse shape of the pluralityof light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a minimum light intensity and amaximum light intensity of the plurality of light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a DC background amount of lightintensity of the plurality of light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of a precharge amount of lightintensity followed by a trigger amount of light intensity amount oflight intensity of the plurality of light signals.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of the plurality of light signalsto delay at least some of the NAPs produced by the one or more nervesthat would otherwise occur.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of the plurality of light signalsto increase a frequency of the NAPs produced by the one or more nervesthat would otherwise occur.

In some embodiments, the control of the light signals provided by thecontroller includes selective control of the plurality of light signalsto decrease a frequency of the NAPs produced by the one or more nervesthat would otherwise occur.

In some embodiments, the apparatus includes an implanted aself-contained battery-powered laser light-generation device.

In some embodiments, the obtaining the plurality of light signalsincludes implanting self-contained infrared (IR) laser device.

In some embodiments, the a transmission medium configured to transmitlight signals from the one or more laser light sources to one or morenerves of each of one or more inner-ear vestibular organs of a livinganimal includes one or more optical fibers configured to guide the lightsignals.

In some embodiments, the one or more laser light sources include a firstlight source and a second light source, wherein the control of the lightsignals provided by the controller includes selective control of thefirst light source to send a first series of pulses during a firstperiod of time and selective control of the second light source to senda second series of pulses during the first period of time, and whereinthe first series of pulses differs from the second series of pulses inrepetition rate.

In some embodiments, the present invention provides an apparatus furtherincluding at least one sensor configured to sense one or more conditionsthat affect balance, and wherein the control of the light signalsprovided by the controller includes selective control of the lightsignals to provide a sense-of-balance nerve stimulation at least partlybased on a signal from the at least one sensor.

In some embodiments, the at least one sensor includes a motion sensor.

In some embodiments, the at least one sensor includes an orientationsensor.

In some embodiments, the at least one sensor includes a muscularstimulation monitor.

In some embodiments, electrical stimulation carried via efferent nervesto muscles is sensed. In some embodiments, the result of the muscularmovement is sensed.

In some embodiments, the muscular stimulation monitor includes a sensorthat monitors eye movements.

In some embodiments, the present invention provides an apparatus thatincludes means for obtaining a plurality of light signals from one ormore laser light sources; and means for delivering the plurality oflight signals to one or more nerves of each of one or more inner-earvestibular organs of a living animal; means for selectively controllingthe plurality of light signals to optically stimulate the one or morenerves in order to control nerve action potentials (NAPS) produced bythe one or more nerves.

In some embodiments, the living animal is a human person. In someembodiments, the living animal is a large non-human animal, e.g., a racehorse or dairy cow. In some embodiments, the living animal is a smallnon-human animal, e.g., a dog or cat.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a pulse width of the plurality oflight signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a duty cycle of the plurality oflight signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling an on-time and an off-time of theplurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a wavelength of the plurality oflight signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a pulse repetition rate of theplurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a pulse shape of the plurality oflight signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a minimum light intensity and amaximum light intensity of the plurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a DC background amount of lightintensity of the plurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling a precharge amount of lightintensity followed by a trigger amount of light intensity of theplurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling the light signals to delay atleast some of the NAPs produced by the one or more nerves that wouldotherwise occur without the plurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling the light signals to increase afrequency of the NAPs produced by the one or more nerves that wouldotherwise occur without the plurality of light signals.

In some embodiments, the means for selectively controlling the lightsignals includes means for controlling the light signals to decrease afrequency of the NAPs produced by the one or more nerves that wouldotherwise occur without the plurality of light signals.

In some embodiments, the means for obtaining the plurality of lightsignals includes implanting a self-contained battery-poweredlaser-light-generation device.

In some embodiments, the obtaining the plurality of light signalsincludes implanting self-contained infrared (IR) laser device.

In some embodiments, the means for delivering the plurality of lightsignals to one or more nerves of each of one or more inner-earvestibular organs includes using one or more optical fibers to guide thelight signals.

In some embodiments, the one or more laser light sources include a firstlight source and a second light source, wherein the means forselectively controlling the plurality of light signals includes meansfor controlling the first light source to send a first series of pulsesduring a first period of time and means for controlling the second lightsource to send a second series of pulses during the first period oftime, and wherein the first series of pulses differs from the secondseries of pulses in repetition rate.

In some embodiments, the present invention provides an apparatus furtherincluding means for sensing one or more conditions that affect balance,and wherein the means for selectively controlling the plurality of lightsignals includes means for controlling the light signals, at leastpartly based on the sensed one or more conditions that affect balance,to provide a sense-of-balance nerve stimulation.

In some embodiments, the means for sensing of the one or more conditionsthat affect balance includes means for sensing motion and orientation.

In some embodiments, the means for sensing the one or more conditionsthat affect balance includes means for monitoring muscular stimulation.

In some embodiments, electrical stimulation delivered via nervesconnected to muscles is sensed. In some embodiments, the result of themuscular movement is sensed.

In some embodiments, the means for monitoring muscular stimulationincludes means for monitoring eye movements.

In some embodiments, electrical stimulation delivered via nervesconnected to eye muscles is sensed. In some embodiments, the eyemovement is sensed to indirectly sense eye muscle stimulation.

In some embodiments, electrical stimulation to eye muscles is sensed. Insome embodiments, the eye movement is sensed to indirectly sense eyemuscle stimulation.

In some embodiments, the present invention provides a method thatincludes obtaining light from an optical source; and transmitting thelight to respective nerves of each of a plurality of inner-ear balanceorgans of an animal. The animal can either be a human or be some otheranimal.

In some embodiments, the transmitting includes transmitting differentamounts of the light through optical fibers to stimulate respectivenerves of each of the plurality of inner-ear balance organs.

In some embodiments, the transmitting includes transmitting differentwavelengths of the light to stimulate respective nerves of each of theplurality of inner-ear balance organs.

In some embodiments, various parameters are adjusted and/or controlled,such as the pulse repetition rate or pattern, the pulse width, the pulseintensity, the wavelength(s), the amount of background constant (DC)optical level, and/or selected multiple simultaneous wavelengths.Multiple wavelengths are provided, in some embodiments, by using aplurality of lasers having different wavelengths. In some embodiments, aplurality of fibers is used to deliver the stimulation light to aplurality of stimulation sites.

In some embodiments, the present invention includes triggers and sensorsthat generate signals that are input to software of the presentinvention, wherein the software analyzes the signals and based on theanalysis, generates control signals that control the parameters, such asfrequency and intensity of light output (e.g., laser pulses) for each ofone or more channels that communicate with the vestibular nucleus. Forexample, some embodiments use sensors such as described in U.S. Pat. No.6,546,291 issued to Merfeld et al. on Apr. 8, 2003, which was describedabove and which is incorporated herein by reference. For example, someembodiments include sensors for detecting characteristics of thepatient's head, eyes, posture and the like.

Some embodiments use one or more implanted VCSEL arrays to directlystimulate the desired nerves, while in other embodiments, one or moreimplanted VCSELs are optically coupled using one or more optical fibersleading to the stimulation sites.

In other embodiments, one or more VCSEL arrays are located external tothe patient's body, and use transcutaneous coupling to one or moreimplanted fiber arrays. In some embodiments, the implanted fiber arraysprovide one or more feedback loops (e.g., a fiber having both of itsends facing outwards from the body) in order to assist couplingalignment. In some embodiments, permanent magnets are used on theimplanted fiber arrays and external VCSEL stimulator to maintaincoupling and assist in coupling alignment. In some embodiments, theimplanted fiber arrays have a bulbous head on each fiber to collect anddirect laser light into the fiber core.

Some embodiments provide programmable and/or reprogrammable control. Insome embodiments, the controller is implanted in the body, and in someother embodiments, the controller is located external to the body andcoupled to an implanted fiber array using transcutaneous coupling (e.g.,some embodiments use a VCSEL array to provide light from thestimulator_.

In some embodiments, electrical signals of the nerves are sensed andused to provide feedback to the controller, in order to better controlthe laser stimulation signal.

In some embodiments, the optical nerve stimulation is used to supplementor override the nerve responses generated by the inner ear organs. Someconditions, e.g., Benign Paroxysmal Positional Vertigo (BPPV), resultfrom over stimulation of nerves in a normally resting position. Throughadditional optical nerve stimulation, the natural nerve responses can besupplemented or overridden. In some embodiments, wider pulse widthoptical nerve stimulations are used to override or reduce the frequencyof natural nerve responses to treat some inner ear conditions.

In some embodiments, the obtaining light includes implanting aself-contained infrared laser device.

In some embodiments, the obtaining light includes implanting aself-contained battery-powered device.

In some embodiments, the animal is a human person. In some embodiments,the animal is not human. Some embodiments further include sensing acondition that affects balance, and wherein the transmitting includestransmitting different light signals to each of a plurality of differentbalance-sense organs to provide the person sense-of-balance nervestimulation.

In other embodiments, the present invention provides an apparatus thatincludes an optical source; and a transmission medium configured totransmit light from the optical source to respective nerves of each of aplurality of inner-ear balance organs of an animal.

In some embodiments, the transmission medium includes a plurality ofoptical fibers, and the optical source couples different amounts of thelight through the plurality of optical fibers to stimulate differentrespective nerves of each of the plurality of inner-ear balance organs.

In some embodiments, the optical source couples different wavelengths ofthe light to stimulate different respective nerves of each of theplurality of inner-ear balance organs.

In some embodiments, the optical source includes a self-containedimplantable infrared laser device.

In some embodiments, the optical source includes a self-containedbattery-powered device.

In some embodiments, the animal is a human person. Some embodimentsfurther include at least one sensor configured to sense a condition thataffects balance, and wherein the transmission medium transmits differentlight signals, based on the sensed condition, to each of a plurality ofdifferent balance-sense organs to provide the person sense-of-balancenerve stimulation.

In other embodiments, the present invention provides an apparatus thatincludes means for obtaining light from an optical source; and means fortransmitting the light to respective nerves of each of a plurality ofinner-ear balance organs of an animal.

In some embodiments of the apparatus, the means for transmittingincludes means for transmitting different amounts of the light throughoptical fibers to stimulate respective nerves of each of the pluralityof inner-ear balance organs. In some embodiments, the means fortransmitting includes means for transmitting different wavelengths ofthe light to stimulate respective nerves of each of the plurality ofinner-ear balance organs. In some embodiments, the means for obtaininglight includes a self-contained infrared laser implantable device. Insome embodiments, the means for obtaining light includes aself-contained battery-powered implantable device.

In some embodiments, the animal is a human person, and the apparatusfurther includes means for sensing a condition that affects balance, andwherein the means for transmitting includes means for transmittingdifferent light signals, based on the sensed condition, to each of aplurality of different balance-sense organs to provide the personsense-of-balance nerve stimulation.

For each of the above embodiments that describe a stimulation of avestibular organ, there are other embodiments of the present inventionthat stimulate any and/or all elements of the vestibular system:inner-ear vestibular organs, CN VIII, vestibular nucleus, or any othercentral process of animal's system.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Although numerous characteristics andadvantages of various embodiments as described herein have been setforth in the foregoing description, together with details of thestructure and function of various embodiments, many other embodimentsand changes to details will be apparent to those of skill in the artupon reviewing the above description. The scope of the invention should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein,” respectively. Moreover, the terms “first,” “second,” and“third,” etc., are used merely as labels, and are not intended to imposenumerical requirements on their objects.

What is claimed is:
 1. A method comprising: obtaining a plurality oflaser-light sources configured to generate a plurality of laser-lightsignals including a first laser-light signal, a second laser-lightsignal, and a third laser-light signal; providing an implantableoptical-emission head configured to direct the plurality of laser-lightsignals toward nerves of an animal, wherein the providing of theoptical-emission head includes providing a plurality of optical-outputports that emit light from a first emitting surface of theoptical-emission head, wherein the plurality of optical-output portsincludes a first optical-output port, a second optical-output port, anda third optical-output port; coupling the plurality of laser-lightsources to the optical-emission head using a plurality of opticalwaveguides including a first optical waveguide carrying the firstlaser-light signal to the first optical-output port, a second opticalwaveguide carrying the second laser-light signal to the secondoptical-output port, and a third optical waveguide carrying the thirdlaser-light signal to the third optical-output port; implanting theoptical-emission head in the animal such that the plurality ofoptical-output ports of the optical-emission head directs the pluralityof laser-light signals toward the nerves of the animal; outputting theplurality of laser-light signals from the plurality of optical-outputports to the nerves of the animal; testing the implantedoptical-emission head to determine which selected subset of theplurality of optical-output ports is most effective for opticalstimulation of desired nerves of the nerves, wherein the testing causesselected subsets of laser-light sources of the plurality of laser-lightsources to emit laser-light signals from the plurality of optical-outputports toward the nerves, wherein the testing includes sensing conditionsthat affect balance of the animal during the testing, wherein theconditions are related to nerve action potentials (NAPs) triggered inthe nerves by the laser-light signals emitted during the testing,wherein the most-effective selected subset of the plurality ofoptical-output ports is determined at least partly based on the sensingof the conditions; and selectively controlling the plurality oflaser-light signals from each of the plurality of laser-light sourcessuch that the plurality of laser-light signals provide controlledoptical stimulation to the desired nerves in order to triggernerve-action potentials (NAPS) in the desired nerves, wherein theselectively controlling includes using results of the testing of theimplanted optical-emission head such that the selectively controlling ofthe plurality of laser-light signals results in the optical-emissionhead emitting laser-light signals from the selected subset of theplurality of optical-output ports that was determined to be mosteffective for optical stimulation of the desired nerves.
 2. The methodof claim 1, wherein the plurality of optical waveguides includes aplurality of optical fibers, the method further comprising assemblingthe plurality of optical fibers in an optical-fiber bundle.
 3. Themethod of claim 1, wherein the selectively controlling of the pluralityof laser-light signals includes controlling a pulse width of theplurality of laser-light signals.
 4. The method of claim 1, wherein theselectively controlling of the plurality of laser-light signals includescontrolling a pulse-repetition rate of the plurality of laser-lightsignals.
 5. The method of claim 1, wherein the selectively controllingof the plurality of laser-light signals includes controlling a pulseshape of the plurality of laser-light signals.
 6. The method of claim 1,wherein the selectively controlling of the plurality of laser-lightsignals includes controlling a DC background amount of light intensityand a maximum intensity of the plurality of laser-light signals.
 7. Themethod of claim 1, wherein the selectively controlling of the pluralityof laser-light signals includes controlling a precharge amount of lightintensity followed by a trigger amount of light intensity of theplurality of laser-light signals.
 8. The method of claim 1, wherein theselectively controlling of the plurality of laser-light signals includescontrolling the plurality of laser-light signals to decrease a frequencyof the NAPs produced by the nerves that would otherwise occur withoutthe plurality of laser-light signals.
 9. The method of claim 1, whereinthe obtaining of the plurality of laser-light signals includesimplanting a self-contained battery-powered laser-light-generationdevice in the animal.
 10. The method of claim 1, further comprisingdelivering electrical stimulation to an inner-ear organ of the animal.11. The method of claim 1, wherein the nerves of the animal are nervesof an inner-ear vestibular organ of the animal.
 12. A method for opticalstimulation of a plurality of nerves of a human person, the methodcomprising: providing an optical-emission head having a plurality ofvertical-cavity surface-emitting lasers (VCSELs) located on a firstemitting face of the optical-emission head and configured to emit aplurality of laser-light signals from the first emitting face toward theplurality of nerves of the person, wherein the plurality of laser-lightsignals are configured to optically stimulate responses in the pluralityof nerves; implanting the optical-emission head in the person;outputting the plurality of laser-light signals from theoptical-emission head to the plurality of nerves of the person; testingthe implanted optical-emission head to determine which selected subsetof the plurality of VCSELs is most effective for optical stimulation ofdesired nerves of the plurality of nerves, wherein the testing causesselected subsets of the plurality of VCSELs to emit laser-light signalstoward the plurality of nerves, wherein the testing includes sensingconditions that affect balance of the person during the testing, whereinthe conditions are related to nerve action potentials (NAPs) triggeredin the plurality of nerves by the laser-light signals emitted during thetesting, and wherein the most effective selected subset of the pluralityof VCSELs is determined at least partly based on the sensing of theconditions; and selectively controlling the plurality of laser-lightsignals emitted from each of the plurality of VCSELs such that theplurality of laser-light signals provide controlled optical stimulationto the desired nerves in order to trigger nerve action potentials (NAPs)in the desired nerves, wherein the selectively controlling includesusing results of the testing of the implanted optical-emission head suchthat the selectively controlling of the plurality of laser-light signalsresults in the optical-emission head emitting laser-light signals fromthe selected subset of the plurality of VCSELs that was determined to bemost effective for optical stimulation of the desired nerves.
 13. Themethod of claim 12, wherein the selectively controlling of the pluralityof laser-light signals includes controlling a pulse width of theplurality of laser-light signals.
 14. The method of claim 12, whereinthe selectively controlling of the plurality of laser-light signalsincludes controlling a pulse repetition rate of the plurality oflaser-light signals.
 15. The method of claim 12, wherein the selectivelycontrolling of the plurality of laser-light signals includes controllinga pulse shape of the plurality of laser-light signals.
 16. The method ofclaim 12, further comprising delivering electrical stimulation to aninner-ear organ of the animal.
 17. The method of claim 12, wherein theplurality of nerves of the human person include a plurality ofvestibular nerves of the human person.
 18. An apparatus comprising aplurality of laser-light sources configured to generate a plurality oflaser-light signals including a first laser-light signal, a secondlaser-light signal, and a third laser-light signal; an optical-emissionhead configured to be implanted in an animal and to direct the pluralityof laser-light signals toward nerves of the animal, wherein theoptical-emission head includes a plurality of optical-output ports on afirst emitting surface of the optical-emission head such that theplurality of optical-output ports direct the plurality of laser-lightsignals from the first emitting surface, wherein the plurality ofoptical-output ports includes a first optical-output port, a secondoptical-output port, and a third optical-output port; means foroutputting the plurality of laser-light signals from the plurality ofoptical-output ports to the nerves of the animal, wherein the means foroutputting includes a first means for carrying the first laser-lightsignal to the first optical-output port, a second means for carrying thesecond laser-light signal to the second optical-output port, and a thirdmeans for carrying the third laser-light signal to the thirdoptical-output port; means for testing the optical-emission head, whenimplanted, to determine which selected subset of the plurality ofoptical-output ports is most effective for optical stimulation ofdesired nerves of the nerves, wherein the means for testing causesselected subsets of laser-light sources of the plurality of laser-lightsources to emit laser-light signals from the plurality of optical-outputports toward the nerves, wherein the means for testing includes meansfor sensing conditions that affect balance of the animal during testing,wherein the conditions are related to nerve-action potentials (NAPs)triggered in the nerves by the laser-light signals emitted during thetesting, wherein the most effective selected subset of the plurality ofoptical-output ports is determined at least partly based on sense datagenerated from the means for sensing; and means for selectivelycontrolling the plurality of laser-light signals from each of theplurality of laser-light sources such that the plurality of laser-lightsignals provide controlled optical stimulation to the desired nerves inorder to trigger nerve-action potentials (NAPs) in the desired nerves,wherein the means for selectively controlling includes means for usingresults of the testing of the implanted optical-emission head such thatthe means for selectively controlling of the plurality of laser-lightsignals emits laser-light signals from the selected subset of theplurality of optical-output ports that was determined to be mosteffective for optical stimulation of the desired nerves.
 19. Theapparatus of claim 18, wherein the means for selectively controlling theplurality of laser-light signals includes means for controlling a pulsewidth of the plurality of laser-light signals.
 20. The apparatus ofclaim 18, wherein the means for selectively controlling the plurality oflaser-light signals includes means for controlling a pulse repetitionrate of the plurality of laser-light signals.
 21. The apparatus of claim18, wherein the means for selectively controlling the plurality oflaser-light signals includes means for controlling a pulse shape of theplurality of laser-light signals.
 22. The apparatus of claim 18, whereinthe means for selectively controlling the plurality of laser-lightsignals includes means for controlling a DC background amount of lightintensity and a maximum light intensity of the plurality of laser-lightsignals.
 23. The apparatus of claim 18, wherein the optical-emissionhead is configured to direct the plurality of laser-light signals towardnerves of an inner-ear vestibular organ of the animal.